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C extension breaking strings

Discussion in 'Luthier's Corner [DB]' started by DuluthDank, Jan 4, 2018.


  1. I just bought a new set of Thomastic Spiro middles, and was trying to get the extended E string up to pitch when it broke. My extension is the type without a wheel on top so it is basically string on wood, where the string has to make an almost 180 degree turn and pass through a hole in the scroll. I had used a pencil to apply graphite to the contact points before putting on the string, but even with that it seems to not have been enough. This is the second time this has happened with a Thomastic extended C (it happened last time when I tried to change the strings), and I've been using the same C string for about 5 years now, because apparently for whatever reason this Pirastro Permanant C can handle my extension where Thomastics can't. It's pretty darn frustrating seeing an over 100 dollar string becoming useless like that before it can even be used, and now I'm debating getting my extension removed so I no longer have to deal with it. I do like the notes and it would be a bummer to lose it (and pay to have it removed), so I'm wondering if there are any alternatives out there to removal. Perhaps there is a way to better prepare my extension before putting on the string than just graphite? Perhaps there is a way it can be modified? extension1. extension2.
     
  2. LouisF

    LouisF Supporting Member

    Apr 21, 2003
    Los Angeles, CA
    Would graphite (lead pencil) help? I have no idea- just a question. I know it's done sometimes on bridges and nuts
    Louis
     
  3. wathaet

    wathaet

    May 27, 2007
    You really should try to modify it for a wheel, but try a pvc tube (or similar) until then.
     

  4. I had been using graphite because that is what I had been told to do in the past...now I am wondering if there are any other wood-friendly lubricants to try. Each time is a 115 dollar experiment, so I want to be fairly optimistic if possible.
     
  5. If modifying it for a wheel would work that would be cool, but I'm wondering how expensive that might be. Considering that it's not built for that in the first place, I'm afraid that that sort of custom job might run me close to the cost of a new extension.
     
  6. robobass

    robobass

    Aug 1, 2005
    Cologne, Germany
    Private Inventor - Bass Capos
    I am fairly well informed as to what is going on in the C-Extension world, and I have never heard of a build without a pulley. From the photos, the extension looks very well made. To do all of this work and no pulley though? Incomprehensible. In your location it shouldn't be hard to find someone who can carve a slot and mount a pulley, and it shouldn't be super labor intensive. Everything else looks tip top.
     
    Last edited: Jan 4, 2018
    salcott and Don Kasper like this.
  7. Don Kasper

    Don Kasper Supporting Member

    You might try affixing a piece of Teflon heat-shrink tubing on the string at the area that passes around the stationary 180 degree turning point.
    NOTE: Not all shrink tubing is made of Teflon - make sure you use the Teflon type. It is slippery.

    Good Luck.
     
  8. Brent Nussey

    Brent Nussey

    Jun 27, 2001
    Tokyo, Japan
    I think it was done a lot like this in the old days, like with machine extensions. Mine was like this when I bought my bass. Lou DeLeone put a piece of black tubing, probably teflon, over the string at the contact point, and the string tuned much more easily. I agree that looking at it, the best solution would be to have a pulley added. I'd be curious to know if the string breaks at the place where it goes around the extension, or where the nut is. I wonder if it might be possible that the nut slot or the way the string breaks back from the nut could be the culprit. It would then make sense that one type of string works, and another (larger diameter?) one doesn't...
     
  9. robobass

    robobass

    Aug 1, 2005
    Cologne, Germany
    Private Inventor - Bass Capos
    Very good! They also make teflon tubing to line brake cable housings on bicycles, although it might be too small. I'd still get a pulley installed though.
     
    Phil Rowan and Don Kasper like this.
  10. robobass

    robobass

    Aug 1, 2005
    Cologne, Germany
    Private Inventor - Bass Capos
    You might get in touch with Scott Jensen in St. Paul. He is an experienced extension builder.
     
  11. I'm talking with a local luthier about this right now. It seems as though a hard plastic would be the least expensive option as a way of reducing friction, as you have suggested. I'm not totally sure that my extension is robust enough to handle a pulley installation, as it does have a bit of a crack running length-wise. Also, it seems like the string broke in the peg box...I'm not sure if that gives anybody any clues as to what the problem is.
     
  12. I'm scheduled to bring in my bass to Scott next week! I hadn't realized he was an extension builder before reading your comment, I guess this means I am in good hands.
     
  13. robobass

    robobass

    Aug 1, 2005
    Cologne, Germany
    Private Inventor - Bass Capos
    Great! I have had occasional contact with Scott over many years. He seems like a very concientious guy.
     
    Last edited: Jan 7, 2018
  14. robobass

    robobass

    Aug 1, 2005
    Cologne, Germany
    Private Inventor - Bass Capos
    Binding at the nut, or in your case, over the curve at the top of the extension, could still cause the string to break at the tuner shaft.
     
  15. Steven Ayres

    Steven Ayres Supporting Member

    Mar 11, 2007
    Northern Arizona
    And that would indicate the problem is drag on the string causing overtension, rather than the break angle over the extension, right?
     
    robobass likes this.
  16. robobass

    robobass

    Aug 1, 2005
    Cologne, Germany
    Private Inventor - Bass Capos
    Almost certainly. The pictures show no break angle issues, but the way the outer wrap is loose and uneven over the top seems to indicate serious friction issues. Wheel!
     
    Don Kasper likes this.
  17. Heifetzbass

    Heifetzbass Commercial User

    Feb 6, 2004
    Upstate, SC
    Owner, Gencarelli Bass Works and Fine String Instruments, LLC.
    I have had 3 Thomastik Spirocore strings break in the last year or two, all low strings. (2 were Extended C's and one was a B going on my 5 string) A couple of Ext. C's with a horrible buzz on the strings, Thomastik replaced at least one of them.

    One the broken strings, there were no issues with the basses, but at tension the inner core just broke.

    I'm staying away from their low strings.

    YMMV,
    Brian
     
  18. LouisF

    LouisF Supporting Member

    Apr 21, 2003
    Los Angeles, CA
    Robobass: you said he was "contentious"; might you have meant "conscientious"? I don't know him. Just checking.
    Louis
     
  19. robobass

    robobass

    Aug 1, 2005
    Cologne, Germany
    Private Inventor - Bass Capos
    Og Geez! I hope No one thought I actually meant what I wrote. Yes! CONSCIENTIOUS!
     

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